3 ms·

By design, braking introduces drag onto the brake disc and in turn creates drag on the wheel. This drag is in opposition to forward momentum and so the rubber o

By design, braking introduces drag onto the brake disc and in turn creates drag on the wheel. This drag is in opposition to forward momentum and so the rubber of the tyre flexes and gives to these forces a little at a time - resulting in slowing your forward momentum. A rail car without rubber takes 10x-50x the distance to brake due to steel on steel friction. Rubber is consumed from the tyre during acceleration, deceleration, and turning. Little rubber granules will roll off. The only time this isn’t happening is when the tyres aren’t in motion. This is why you bring extra tyres to track day.

raverbashing 3y ago
Correct. I don't see why regenerative braking would be any different Tire wear would be a factor of deceleration, regardless if it's from a traditional brake or electrical braking
- silversmith 3y ago
  One possibility - if you do regen braking as in one pedal driving, there is a lot less coasting to stop, and I imagine that is less stressful on the tires.
  - jtc331 3y ago
    It's an interesting idea, but in general you don't come most of the way to a stop coasting in an ICE car unless you're already at a low speed. Usually you coast some, and then you have to brake significantly still.
- reactordev 3y ago
  When the wheel is just coasting (no additional torque supplied) you have the least amount of friction (assuming you’re going in a straight line) against the rubber. The issue with fly-by-wire systems is there’s no coasting. An ECU is constantly supplying PWM like torque pulses to the wheels to keep the speed constant. My OneWheel burns through rubber because of this. My EV as well. Yet my ICE vehicles or vehicles with a CVT/Open Diff that let the wheels run free don’t suffer from having to change the tires every few months. I believe that’s in corroboration with what the article is claiming. The soft compound tires for ride comfort get absolutely chewed. There’s ripple like wear from the motors.
buran77 3y ago
In motion the friction coefficient of rubber on asphalt (0.67) is not that far off from steel on steel (0.57) according to the internet [0]. That orders of magnitude difference in braking distance is more a result of train cars weighing 30-80t. This comment does feel like talking to ChatGPT though, with the detailed clarifications the discussion didn't really require. [0] https://www.aplusphysics.com/courses/honors/dynamics/images/CoeffFriction.gif https://www.aplusphysics.com/courses/honors/dynamics/images/...
- londons_explore 3y ago
  Trains take a really long time to stop because the tracks frequently aren't clean - even a tiny bit of leaves or grease can cut the coefficient of dynamic friction down 10x
- londons_explore 3y ago
  The mass of a vehicle does not determine the braking distance, assuming the braking is coefficient of friction limited.
  - buran77 3y ago
    It does but not because it influences friction at the wheel contact point (the mass cancels out in that formula). If braking is done entirely in "wheels locked" fashion then all that matters is the friction coefficient between the wheel and the track. But most braking is not like that. A train will only lock the wheels in emergency braking as that will apply larger braking force than otherwise available. In normal braking the friction between the pads and the wheel is the important one and in that case the stopping distance is determined by how much of the energy of the moving vehicle you can bleed through the force you apply with the braking pads. More mass/speed, more energy, more time needed to apply the xxxxN of force to the wheel and convert the energy to heat. The energy of the moving vehicle scales with its weight while the maximum force a friction braking system can apply doesn't. The science of braking is even more complicated than that, materials heat up or melt, friction coefficients change, tires behave differently under different loads, ABS systems kick in, etc. These are deceptively complicated topics. The formula for friction also doesn't contain surface area and yet we use wide tires and big brake pads. But the bottom line is that in a real life scenario (as in not in simplified formulas on paper) the weight of the vehicle very much influences the braking distance.

raverbashing 3y ago

Correct. I don't see why regenerative braking would be any different Tire wear would be a factor of deceleration, regardless if it's from a traditional brake or electrical braking

silversmith 3y ago
One possibility - if you do regen braking as in one pedal driving, there is a lot less coasting to stop, and I imagine that is less stressful on the tires.
- jtc331 3y ago
  It's an interesting idea, but in general you don't come most of the way to a stop coasting in an ICE car unless you're already at a low speed. Usually you coast some, and then you have to brake significantly still.
reactordev 3y ago
When the wheel is just coasting (no additional torque supplied) you have the least amount of friction (assuming you’re going in a straight line) against the rubber. The issue with fly-by-wire systems is there’s no coasting. An ECU is constantly supplying PWM like torque pulses to the wheels to keep the speed constant. My OneWheel burns through rubber because of this. My EV as well. Yet my ICE vehicles or vehicles with a CVT/Open Diff that let the wheels run free don’t suffer from having to change the tires every few months. I believe that’s in corroboration with what the article is claiming. The soft compound tires for ride comfort get absolutely chewed. There’s ripple like wear from the motors.

buran77 3y ago

In motion the friction coefficient of rubber on asphalt (0.67) is not that far off from steel on steel (0.57) according to the internet [0]. That orders of magnitude difference in braking distance is more a result of train cars weighing 30-80t. This comment does feel like talking to ChatGPT though, with the detailed clarifications the discussion didn't really require. [0] https://www.aplusphysics.com/courses/honors/dynamics/images/CoeffFriction.gif https://www.aplusphysics.com/courses/honors/dynamics/images/...

londons_explore 3y ago
Trains take a really long time to stop because the tracks frequently aren't clean - even a tiny bit of leaves or grease can cut the coefficient of dynamic friction down 10x
londons_explore 3y ago
The mass of a vehicle does not determine the braking distance, assuming the braking is coefficient of friction limited.
- buran77 3y ago
  It does but not because it influences friction at the wheel contact point (the mass cancels out in that formula). If braking is done entirely in "wheels locked" fashion then all that matters is the friction coefficient between the wheel and the track. But most braking is not like that. A train will only lock the wheels in emergency braking as that will apply larger braking force than otherwise available. In normal braking the friction between the pads and the wheel is the important one and in that case the stopping distance is determined by how much of the energy of the moving vehicle you can bleed through the force you apply with the braking pads. More mass/speed, more energy, more time needed to apply the xxxxN of force to the wheel and convert the energy to heat. The energy of the moving vehicle scales with its weight while the maximum force a friction braking system can apply doesn't. The science of braking is even more complicated than that, materials heat up or melt, friction coefficients change, tires behave differently under different loads, ABS systems kick in, etc. These are deceptively complicated topics. The formula for friction also doesn't contain surface area and yet we use wide tires and big brake pads. But the bottom line is that in a real life scenario (as in not in simplified formulas on paper) the weight of the vehicle very much influences the braking distance.